Some medical researchers theorize that this disease is similar to Multiple Sclerosis in humans.
There are also other neurological conditions which may be diagnosed improperly as DM, therefore definitive testing should be carried out to assure proper diagnosis. Chronic disease or repeated exposure to chemicals, or pest born diseases, such as "tick fever" will also result in neurological changes. It is probably wise not to rule out environmental influences on the incidence of this or other neurological disease.
This URL is a page by Dr. R.M. Clemmons, one of the foremost researchers on DM in the German Shepherd Dog and related breeds. It is a good summary of the disease, its diagnosis, and his treatment stratagy for those breeds. Dr. Clemmons has not diagnosed or treated DM in Kerry Blue Terriers. If you wish to try any of the treatment protocols, please be sure to consult with your own veterinarian or neurologist to make sure that there will be no adverse interactions with other medications or treatments (this include herbal treatments).
A Kerry Blue with Degenerative Myelopathy, by Richard Noe